If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content
Current time:0:00Total duration:5:48

Video transcript

- [Voiceover] So unfortunately there aren't any lab or imaging tests to confirm that someone definitely has schizophrenia. But we might be able to use several types of tests to rule out potential causes of schizophrenia and symptoms of psychosis. Here's an example. If you got a urine or a blood test and there were substances present, like alcohol or hallucinogens, we might be clued in to those being potential causes, right. As another example, you could have an imaging test, like computed tomography or better known as a CT scan, or a magnetic resonance imaging scan or MRI, to look for the possibility of a brain tumor that could be causing symptoms of psychosis and schizophrenia. But in order to actually diagnose someone with schizophrenia, we need to go through and look for all of the symptoms associated with it before coming to a conclusion. And one way we can try to do this is by asking the patient questions. So we might ask if they've noticed anything suspicious going on around them, which is a way we can probe for signs of delusions. Specifically in this example we're considering signs of paranoid delusions, right. But another question we might ask is if they've been hearing any voices, other than ours. And here we're looking for signs of auditory hallucinations. Or we might ask them to describe what they see around the room, which is looking for signs of visual hallucinations. One potential issue with this, though, is that sometimes the information provided by the patient might actually be affected or skewed in some way due to these delusions and hallucinations. So we might try to enlist the help of family members or friends. Besides questions for hallucinations and delusions, though, you can ask questions to probe for emotional symptoms, like anhedonia, by asking them what sorts of hobbies they enjoy, or in the case of anhedonia, used to enjoy. And once we've sort of probed for these symptoms of schizophrenia, and if they are indeed present, they need to stay present for at least six months before an actual diagnosis can be given. If the symptoms are there but maybe it hasn't been that long yet, we might consider a diagnosis of schizophreniform disorder, which has the same symptoms as schizophrenia but the duration is between one to six months. About 70% of patients that are diagnosed with schizophreniform go on to be diagnosed with schizophrenia. So now that we've sort of confirmed the presence of schizophrenia, why is it even there in the first place? Well, that's a really tough question. And by and large, the answer is still a pretty big mystery. But scientists have been able to gather a few clues. One of the big reasons why it's so tough to figure out is that the symptoms and its diagnosis are pretty uniquely human, meaning that it's hard to imagine using an animal model, like mice or rats, in the lab to figure out what's causing it, like, we can use for things like cancer research. One group that we tend to focus on, though, are the neurotransmitters in our brain. One that especially seems to be involved is dopamine. And one clue that dopamine gives us is that a large majority of antipsychotic medications block one of the dopamine receptors to some degree. And this guy's called dopamine receptor D2. This suggests that increased dopamine levels might be involved for people with schizophrenia since blocking these receptors can help with symptoms. Another slightly frustrating clue, though, is that antipsychotic medications are neither universally or completely effective. So not only do they not work for everyone, they don't hit all the symptoms either. And this clue suggests there's probably more to the story than just D2 receptors. And adding to that puzzle, making it even more confusing, is that the most effective antipsychotic medication for schizophrenia seems to be a weak D2 antagonist. And with that said, research remains ongoing regarding the roles of dopamine and other neurotransmitters like GABA or glutamate and acetylcholine. Outside of neurotransmitters, though, a couple other clues gives us some additional information. And genetics are one of those. >From twin studies, where we look at identical twins, we found that there's a 50% chance of developing schizophrenia if an identical twin with 100% the same DNA has been diagnosed. If they're fraternal twins, so they're not identical and they have 50% the same DNA, there's about a 15% chance of developing schizophrenia when the other already has it. And this information seriously hints at a genetic component, right, although no specific genes have been found yet. And then the counterpart to genetics is environment. And development of schizophrenia has also been linked to the kind of environment you develop in, with particularly high associations with things like prenatal complications, which would be like premature labor or situations where the fetus didn't get enough oxygen. Another environmental factor, though, could be maternal infections. And we've seen that there's this increased risk for babies born during the winter and early spring months, which is thought to be connected to the mother's exposure to infectious diseases, like influenza. Though the mechanism behind this is unclear, it's thought to be due to this immune response in mom rather than the actual infection itself. Some autoimmune disorders have also been linked to schizophrenia, like Celiac's disease where the patient's immune system launches attacks on their own small intestine after the ingestion of gluten. Finally, cannabis use has also been linked to an increased risk of developing schizophrenia.